1. Technical Field of the Invention
The present invention relates to a roadside detection system that detects a location of an end portion of a road on which the vehicle travels, and to a driver assistance system and a roadside detecting method.
2. Related Art
As a technique for detecting a roadside, it is known that a laser beam is emitted to scan a range, detect a distance (objective distance) to a target and estimate a region where the objective distance drastically changes (i.e. a region where there is irregularity) as a roadside. For example, JP-B-4100269 discloses such a technique.
However, if there is no irregularity on a roadside, a region where an objective distance drastically changes cannot be detected with the technique mentioned above. Therefore, a roadside may not be detected using this technique. For example, the technique mentioned above is able to detect a roadside having irregularity, such as a wall surface (e.g., mountain surface) or a cliff as shown in FIG. 1A, or a guard rail or a curb as shown in FIG. 1B. However, the technique is not able to detect white lines or other road marks that define areas having no irregularity, such as a road shoulder and a lane dedicated to two-wheeled vehicles, as shown in FIG. 2.